1. Field of the Invention
The present invention relates to a data measuring device which measures data relating to operation of a machine tool.
2. Description of the Related Art
In a factory with a plurality of production lines, a host computer is used to collect operating data to monitor the operating states of the respective production lines. The collected operating data is data indicative of the operating states of various industrial machines such as machine tools or conveyor devices installed on the production lines. The operating data includes, for example, the number of production units, information on whether the respective machines are in operation, or whether there is any alarm notification resulting in shutdown, etc.
The operating data collected by a conventional host computer is generally transmitted from a number of industrial machines to the host computer simultaneously, since the sampling period is relatively long and the data amount is small. However, in recent years, there has been a need to measure not only such operating data, but also physical data relating to the operations of a drive shaft of a machine tool in real time. The physical data of a drive shaft may include, for example, the position or speed of the drive shaft. The physical data of a drive shaft is useful information for investigating the cause of machining defects of workpieces or for improving the machining precision.
However, physical data of a drive shaft utilized for the above-mentioned purpose has to be measured in short sampling periods. For this reason, in a production system in which a large number of machine tools simultaneously operate, a large amount of data is communicated in a short time, there is a risk of the communication line being insufficient in the processing capability, resulting in failure to collect data.
Japanese Patent Publication No. 2000-210800 discloses a monitor device for industrial machines, which is configured to store information indicative of the operating states of an industrial machine as continuous waveform data in time series and to transmit the stored waveform data to a diagnosis terminal via a network.
Japanese Patent Publication No. 2004-013665 discloses an operation management system which manages the operating states of machine tools, in which storage devices connected to NC devices one to one are used to store data relating to the operating states of the machine tools to transmit the stored data to a management device.
According to the related art described in Japanese Patent Publication Nos. 2000-210800 and 2004-013665, the measurement data from the machines to be measured is stored once and the stored data is transmitted to a monitor device or management device. Therefore, it is necessary to provide the machines with additional storage devices at the relay points of the network, etc. This requires an installation space, which in turn increases the size of the system and increases costs.
Therefore, there is a need for an inexpensive and compact data measuring device which can reliably measure physical data of a machine tool.